It is known to purify indium from silicon by baking an indium melt in an atmosphere containing water vapour. The method is based on the oxidation of the silicon in the melt to either silicon dioxide (SiO.sub.2) or silicon monoxide. SiO.sub.2 from the walls of the quartz container has hitherto been present at the baking temperature which imposes restrictions on the combinations of temperatures and water vapour pressures that can be used. The reason for this is that the reaction reverses, i.e., silicon is transported from the walls of the container to the melt in case the water vapour pressure is too low.